Montana DEMOCRAT Max BAUCUS was elected to the United States Senate in 1978, the same year I graduated from the eighth grade. In the ensuing 35 years, I have held about 10 different jobs — including working the counter at a popcorn shop. Max has held one. With his unexpected retirement announcement last week, that trove of institutional knowledge will be lost when he leaves the Senate next year. But he’s not going quietly. Max has had a busy month. And if he gets his way, he’ll be the center of attention until he walks out the door.

Three decades in the Senate is rare; 30 years on the Senate Finance Committee sets the standard. As chairman of that tax-writing panel, Baucus led the effort to craft and pass Obamacare through the Senate. So it made news last month when he called the health care law “a huge train wreck coming down.” His candor reflects the reality he sees on the ground. The federal government has just four months before an October deadline to design and implement online insurance exchanges to serve 20 million people across 34 states. It is woefully behind schedule.

Unencumbered by the political pressures of a reelection campaign, Baucus is in a position to call out both the failure of federal officials to prepare for implementing Obamacare as well as the unintended consequences of its complex regulations. While it is never easy to buck one’s own party leadership, it’s familiar ground for Baucus, who has taken on the role many times throughout the years — and several times in just the past few weeks.

Montana’s motto is “Big Sky.” Politically, the state is big red, voting for the Republican in each of the past five presidential elections. So no one was surprised to see Baucus buck his party on gun control votes in early April. More unusual, however, was the criticism he leveled at Democratic Leader Harry Reid recently for bypassing the Finance Committee and sending an online sales tax bill straight to the Senate floor.

Reid has been notorious for circumventing Senate committees, and Baucus seems to have had enough. In a bipartisan letter, Baucus pointed out that the bill in question erodes the rights of states wishing to opt out of the tax scheme, while subjecting businesses to the auditing and enforcement regimes of hundreds of state and local taxing jurisdictions across the country.

Using tactics usually reserved for more partisan confrontations, Reid refused to move the legislation through committee hearings and markup, and denied a vote on the amendment allowing states to opt out of the tax scheme. “This bill is not ready for debate on the Senate floor,” observed Baucus. And he’s right.

If states are given powers to enforce tax collections outside their borders, what comes next? States could easily argue that power plant emissions or tobacco sales next door affect their own citizens’ health and state medical costs. Will they lobby to expand these new interstate enforcement powers to state environmental and health regulators as well?

The bill may well die in the House, but Baucus’s fires are stoked. He’ll need that energy if his final 18 months in the Capitol are to yield a victory on tax reform, his ultimate goal.

For many outsiders, congressional pronouncements on tax reform conjure up images of Don Quixote taking on a windmill: full of commitment and good intent, but delusional nonetheless. For a member like Baucus, who served on the Finance Committee during the last overhaul in 1986, it was the Senate’s finest hour. As The New York Times reported, the bill was passed out of committee on a 20-0 vote, and Chairman Robert Packwood received a standing ovation.

Cutting a comprehensive budget deal that includes a tax reform target would increase the chances for success. But with or without a “grand bargain,” achieving the dream will require Baucus to use every ounce of strength and political capital at his disposal. His decision to cast off the chains of a reelection struggle just might provide him with the advantage needed to transform high aspirations into an unprecedented final act.

John E. Sununu, a former Republican senator from New Hampshire, writes regularly for the Globe.